Method and apparatus for size reduction



Filed Ah 13. 1941 s Sheets-Sheet 1 a ign-Mmany.

1943. R. BUTLER 2,331,172

METHOD AND APPARATUS FOR SIZE-REDUCTION Filed Aug. 13. 1941 3 Sheets-Sheet 2 1521 2671207: EoefZ'AIBu Z'ln:

Patented Oct. 5, 1943 METHOD AND APPARATUS FOR SIZE REDUCTION Massachusetts Application August 13, 1941, Serial No. 406,713

19 Claims.

My invention relates to size-reducing methods and apparatus.

From' one aspect, my invention relates to an apparatus for reducing or crushing materials, such as, but without limitation thereto, relatively finely divided ores. Among the purposes of my inventionfrom this aspect are an increase in the efiiciency of reduction and in economy of power, and a continuous automatic feed whereby the mass undergoing reduction may, though it does not necessarily constitute the sole control means for material entering the apparatus, serve to control the admission of new particles to the zone of reduction to take the place of reduced particles which escape. Another purpose is the provision of an improved apparatus inwhich the load undergoing reduction may be subjected to reducing forces in a very effective manner without subjecting the same to impacts at the ends of the reciprocatory movements which attend and indeed provide a very large percent of the size-reducing action.

From another aspect, my invention relates to an improved method ofsize-reduction. In the practice of my invention from the latter aspect I oscillate or reciprocate a load of particles through a defined reducing zone, such zone desirably defined by an oscillated, arcuate, and for many materials desirably annular, reduction chamber and including the space throughout at least a substantial portion of an annulus, and

It will be evident that the size of the material to be reduced in size and the nature of the materialthe difliculty of crushing its particlesing action. Accordingly, with such material, a quantity of size-reducing media will normally be employed sufilcient continuously to cover the feed ingress means completely both when the mill is idle and also whenthe chamber load is in such relative position in the zone of reduction that the feed ingress means is in its most proximate relation to an end of the load. The entering material must then enter the load through the spaces between the size-reducing media, either in contact or spread more or lessby reason of chamber load movements and the presence of material particles. Thereby passage of material through the reduction zone without being subjected to a size-reducing action therein will be, practically speaking, precluded. With such conditions the feed rate may be controlled by the size of the media and by the total areaand the arrangement of the feed ingress means, and

will both be of substantial efiect upon the specific apparatus, and as well upon the method of fee control utilized.

When the material to be ground, wet or dry,

possesses a high degree of fluidity, so to speak,

the discharge orifices provided for the escape of .material from the reduction zone in their smallest dimensions may in many cases be as large as or even substantially larger than, the size of the entering material particles. Under such cirinto the reduction zone past the ends of the load would not be practically permissible, as much of the material could pass out of the reduction zone without undergoing any substantial size reduccumstances, free inlet of material to be reduced a relatively uniform feeding of material into the reduction'zone will be obtained because, as will later appear, the 'compactness' of the load and its instantaneous speed of movement in the reduction zone will vary inversely. When necessary or desirable, as hereinafter more fully explained, it is also within-the scope of my invention to place the escape means for material from the reduction zone in angularly displaced relation to the inlet means so as to compel movement of the material substantial distances longitudinallyof the zone between its ingress and discharge and thus insure to a further degree its subjection to the action of the size-reducing media.

- When the size of material in the entering feed is larger the quantity of size-reducing media need not be such as constantly to maintain the feed ingress means covered (although it may still be desirable to use a quantity such as has been suggested) for then the load will, upon the commencement of feed supply, automatically substantially immediately build up its cumulative volume to such a point that automatic feedcontrol will be maintained. It will be found that even with fairly substantial sizes for the larger particles of entering material, particle entry into interstices in the upper surface of the load will be possible either due. to momentary spacings as the components of the load move relative to each other, or due to attrition or other sizereducing action at and against the top of the load reducing the size of larger particles. When the load is below a volume necessary to cover the feed ingress, means at all times material entry past the ends of the load will rapidly bring up the load volume to a quantity necessary for automatic teed control by the load. The nature of the feed control will thus be leento vary with the quantity of size-reducing media, the

A 2,331,112 UNITED STATES PATENT OFFICE size of the entering feed, and-the fluidity, so to reduction. One more specific object is to provide an improved method of size-reduction for relatively very fine material. Other objects. of the invention will appear from'time to time in the course of the specification and claims.-

This present application includes material from and is a continuation in part of each of my copending applications Serial Nos. 164,296, filed Sept. 17, 1937 and 397,305, filed June 9, 1941.

In the accompanying drawings, in which for purposes of illustration an illustrativeembodiment of my invention from its apparatus aspect is shown, together with certain modifications,

Fig. 1 is a horizontal sectional view-through the improved mill, taken on the plane of the line l -l of Fig. 2, with some parts shown in plan.

, Fig. 2 is a front elevation of the mill with the front cover broken away to show a portion of the size-reducing chamber.

Fig. 3 is a vertical section on the line 3-3 of Fig. 2.

Fig. 4 is an enlarged section on the line 4-4 of Fig. 3. I

Figs. 5 and 6 are sections respectively on the planes of the lines 5-5 and 6-8 of Fig. 4, showin: details of construction.

11g. 7 is a vertical section, taken perpendicular to the axis of oscillation of the reducing chamber, illustrating the reducing chamber at the end of its oscillation counterclockwise, toward the right.

Fig. 8 is a view similar to Fig.-'? showing the reducing chamber in mid position-and turning clockwise.

Fig. 9 is a fragmentary view, on a reduced scale, on a plane similar to thatof Fig. 4, showing a modification.

Fig. 10 is a view similar to Fig. 4, but on a somewhat reduced scale, showing a modification.

Referring to the drawings, and momentarily particularly to Figs. 3 and 4, it will be observed that material to be reduced in size may be supplied through an inlet hopper l and that it passes thence along any suitable fixed chute or spout 2, the material passing down this fixed chute or spout being indicated at A in Fig. 3. The spout 2 maybe mounted in any suitable relation to a housing generally indicated at. .3, which housing is mounted upon any suitable base 4 and has, as shown, a circumferential cylindrical wall 5, an end wall or cover 6, and an opposite solid end wall I, formed witlrthe bearing support sleeve 8 which mounts a suitable bearing 5 for the shaft Hi to which a size-reduction chamber structure later described is secured. The shaft I is shown as provided with a tapered polygonal end II to which there is secured ahub member I2 which carries a circular plate member l3 suitably secured as by welding to the inner, herein cylindrical, wall 14 of a size-reducing chamber element l5.- Webs l6 strengthenthe inner wall l4 and attach it more securely to the circular 'plate member l3.

.The size-reducing chamber element l includes also an outer arcuate wall I1 and opposite side walls l8 and IS. The walls l4 and I! are coaxial with the shaft l0. a

The inner wall M of the size-reduction chamber is provided with a mouth 2| atthe outer end of a feed passage 22. The feed passage communicates at its lower end with the reducin chamber proper 23, and at its upper and opens into a cylindrical chamber 24 into whose interior the lower, herein horizontal, end of the chute 2 extends, there being provided, if desired, any suitable means for sealing any opening between the exterior of the chute end and the coaxial mouth of the chamber 24. At 25 there is provided a suitable orificed plate for the purpose of providing a feed ingress opening proper.

The outer wall I! of the element I5 is provided with discharge grates 26, herein two being 4 shown in Fig. 4, neither arranged directly opposite the feed inlet opening 2|, but each so disposed that material will have to move longitudinally of the chamber in passing from the feed inlet todischarge. It will be clear that this arrangement is illustrative of a preferred design for particular conditions, and that the discharge grates may be otherwise arranged, as for example the grate may extend opposite the inlet or if desired it may be continuous through any suitable extent of or be provided completely around the outer circumference of the chamber 23. Also evidently more than one ingress opening may be used and both the feed ingress opening or openings and the discharge opening or openings may be arranged in the chamber walls at points other than at the inner and outer walls 14 and H, as for instance in the side walls ll V and I9. In Fig. 10 an arrangement is shown in which the discharge grate extends throughout half the circumferenceof the-reduction chamber, with the feed opening opposite the central portion of the discharge grate. In lieu of the orificed plate 25 and the discharge grate, it will be evident that the walls of the chamber may be perforated at suitable points or the ingress and egress openings be otherwise suitably provided.

The inner wall l4 of the size-reducing chamber element IS, the lateral walls It and ",and

the .outer walls II are desirably provided with rubber or other suitable liners, as shownat 28,

for the purpose of minimizing wear.

The outer wall ll of the size-reducing chamber element is strengthened with circumferentially extending ribs 29, and the side walls I! and. I9 are reinforced with ribs 38, herein shown as extending radially.

The size-reducing-chamber element I5 is arranged in a generally circular chamber 3| from which material passing out of the size-reducin chamber through the discharge grates may be discharged through an opening 32 in the base 4.

The load in the reduction chamber 23 is indicated at B. Desirably, though this is subject to wide variation to meet different conditions, the load comprises a charge or mass of reducing media such as balls, and these balls may desirably be of varied sizes, as indicated at C1, C2, C3. These balls have associated with them in the load during the size-reducing operation, and work against, particles undergoing crushing which diminish in average size as they move from the inlet to the discharge.

In the employment of the structure described, I impart a rotary oscillation to the chamber element l5 about the axis of the shaft HI. While various means for efiecting this oscillation are obviously possible, a suitable illustrative means is shown in Figs. 1 and 3. 35 indicates a driving shaft, which may be driven in any suitable manner. This shaft is shown as mounted in antifriction bearings 36 mounted in seat 21 formed in the walls 38, 39 carried by the base 4. The

shaft 35 carries opposed crank disc 40 connected by a crankpin 4|, and aconnecting rod or link 42 pivotally supported at one end by the crankpin 4| is, at its opposite end, pivotally connected to a pin 43 carried by depending arms 44 secured to the shaft Ill. be understood that as the shaft 35 is driven in It will thereforeany suitable manner, as through a reduction partition of Fig. 9, butby utilizing a chamber" of diminishingcross section, either from its lowermost point when in neutral position, or of diminishing cross section at op osite sides of a central portion of uniform diameter, an increased decelerating action on the load may be secured as it moves upwardly due to an action analogous to a partial impact as the load moves into portions of diminishing cross sectional area. And by utilizing a U-shapedchamber with the upright arms of the U of suificient length, de-

sirable results may also be accomplished. By locating the discharge grates as shown in catory movement of-the chamber load wlthin the I chamber 23.

For the size-reduction of relatively fine material particles, for example, the chamber 23 may be truly annular, but for larger material, or meterial'harder to crack there may be provided a dividing wall as at 41 (see Fig. 9) of a length to provide the desired impact, at a location diametrically opposite the opening 2|; Obviously, the length, circumferentially, of this wall, where such a wall is used, will be varied to suit difierent conditions. Also, as respects the herein disclosed method of controlling the feed of the material to be ground by causing it to be admitted to the mass under reduction solely by way of the interstices at the circumferentially inner face of the moving mass, the chamber 23may have end walls defining its length provided in any other 7 suitable way.

From the foregoing description it will be understood that the rotary oscillation or reciproe cation of the reducing chamber element l5 reciprocates, during normal size-reducing operation, the load B which includes the particlesto be reduced and reducing medium elements. The reducing media and the particles to be reduced are intermingled with each other in the chamber. provided the load may be caused to change its directions of movement by engagement with this wall or walls and direct thrusts on the load be received from the latter. When the size of the particles fed to the mill is small enough and/or the resistance of the material to cracking is sufficlently low, the partition need not be used, and

. impact against transverse walls at the ends of the reducing chamber may be dispensed with and a gravity and friction stop and reversal'of the load at each stroke may be practiced most successfully. Forthis desirable method of operation, the inertia of the load. the time of stop, reversal, and the distance through which the forces are applied must all be properly determined. The inertia must not, for this operation,-

be so great as to prevent starting the chamber load; the stroke time must be great enough to insure more than mere vibrationof the chamber When partitions or a dividing wall 41 is Fig. 4 for example, there may be eifected a longer retention. within the chamber 'of the ,material to be reduced in size, and accordingly an increased grinding in a' single pass may be efiected. The

nature of the discharge means will, however, ob-

viously depend on the material feed, the size of the particles fed, the amount of liquid in the pulp when wet grinding is being carried on, the rate of feed, etc., and it is to be understood that my invention in its broader aspects is not limited to the discharge arrangement shown in Fig. 4, no to that shown in Fig. 10;

With large charges of size-reducing media or an ingress opening of considerable arcuate extent a suitable grating across the feed ingress" opening may be provided to prevent the sizereducing media from working up into the feed supply passage 22 and with a grated construction the angular extent of the feed-opening may be greatly increased if necessary to enable, say, i the successful grinding of thick pulp. I

It will be noted that with this apparatus an the improved process which it is adapted to effect, the load will be reciprocated within the annular chamber and will be subjected to centrifugal or radial pressure due to the partial rotative motion of the load about the axis of oscillation of the chamber element IS. The load will also be subjected to longitudinal pressures during reversals of longitudinal (arcuate) movement as it is brought to rest by gravity and by friction on the walls, particularly the outer and lateral walls of the chamber 23, as it moves upwards in the upwardly extending opposite sides of the annular chamber. Moreover, the tendency of the load to move rectilinearly or tangentially'as it moves in the arcuate '(annular) chamber produces additional thrusts contributing to the efliciency of size-reduction. Furthermore, the very length of the load will contribute to the longitudinal pressure reduction as the longitudinal compactingduring acceleration and deceleration will sub* ject the particles within the -load to pressures longitudinally of the load,

It will be appreciated that, depending upon the load volume, the lengthlarc) of oscillation, etc. the load will be reciprocated arcuately back and forth between positions in which its leading end load; and the. stroke must be long enough for the desired effect on the load. 'It should be understood, however, that load reciprocation out of phase with chamber oscillation is possible within the scope of my invention, for example,

may extend upwards past the horizontal plane in which the axis of oscillation lies while its lower end may approach the vertical plane including such axis, but this will naturally vary with the quantity of size-reducing media, the range of oscillation, the speed of oscillation, the length circumferentially of the chamber of the feed inlet, etc. The movements of the load relative to the chamber and the range of oscillation of the chamber will be varied to meet conditions, but by reference to Figs. 4, 7 and 8 the operation of the load in the chamber may be illustrated. In

Fig. 7 the rocker is illustrated in extreme right or counterclockwise position, that is, as having come to rest and being about to start clockwise movement. The chamber load is not yet at rest, and because of the greater inertia of the outer portion of the load it tends to move upwardly further than the portions nearer the center of oscillation. The load is decelerating, and has been decelerating for a substantial period, because of the deceleration of the rocker, and as the rocker starts its opposite movement the bringing of the load to rest will be expedited. It may be noted that frictional deceleration due to the chambers slowing and coming to rest, gravital deceleration due to the increasingly vertical movement of the center of gravity of the load, and frictional deceleration as the chamber moves oppositely to the load all contribute to bringing the load to rest. Theload is then accelerated, by gravity and by friction, to the left, and in the position of Fig. 8, when the chamber is at midtravel clockwise and moving at substantial veloc! ity, the load has flattened out at its upper end and is moving to the left. There is probably. maximum load velocity also at about this in--'- stant, for from the relative position of Fig. 8 there will be a deceleration of the chamber walls. From this time on, to the instant when clockwise movement of the chamber ends the chamber walls will decelerate, and deceleration forces will be exerted on the load by its confining'chamber walls. Probably the load is not, however, brought to restuntil materially after the chamber again starts to the right, because of the inertia which this load attains. The load will be noted, from the illustrative description given, to be reciprocated within the reduction zone within the annular chamber, to be subjected to centrifugal and tangential thrusts against the outer wall'of the chamber, to the action of gravity, to longitudinal pressures as the load decelerates with its forward portions moving upwardly nearly vertically during the latter, portions of load movement in either direction, and to longitudinal compacting forces especially during deceleration. Desirably, the quantity of size-reducing media may be made sufficient to mask the feed opening when the chamber is empty, but in any event the load length will be automatically maintained, and the compactness of the load will be so maintained that the portion of the annular chamber opposite the feed opening will be continuously so filled that the load will regulate feed ingress and automatically maintain the load volume,

When, however, very fine material is to be reduced in size, and very fluid material, the provision of a charge ,of size-reducing media'suf- 'ficient in volume tomaintain the feed inlet covered by the size-reducing media at all times becomes very desirable, and from one aspect of the method phase of my invention I consider this a definite contribution to the art. Then, by suitablydetermining the sizes of the reducing media, by properly selecting the size and location of the opening oropenings through which the material may enter the chamber, and by providing within the chamber a large enough quantity of size-reducing media, and by properly controlling the range of oscillation it will be possible to preclude the free passage of any material through the chamber without subjecting it to passage through the media mass. In this method of feed control the moving mass of size-reducing media and the material admitted thereto will, under normal supply of material to the apparatus, continuously cover the feed ingress opening so that the flow of material through the size-reducing chamber will be wholly confined to flow through the interstices between the components of the mass. Under such conditions the entering material will be precluded from entry to the reduction chamber past the ends of the moving mass of size-reducing media and material admitted thereto, in all positions thereof in its path of oscillatory movement, so that the material is normally confined to passage through the reduction zone sub- 10 stantially wholly by way of said interstices. Under such conditions the cumulative discharge orifice area may materially exceed the maximum material ingress area, and material which has forced through the chamber-confined mass of be materially extended in duration. It is to be clearly understood that while I consider the method of size-reduction of fine and free-flowing material which involves a normal continuous masking of the feed ingress means by the sizereducing media per se', and the selection of the media sizes under such circumstances as thereby to control or at least measurably regulate the rate of material entry and its distribution within the load, my invention both in its broader method aspect and in the apparatus aspect is in no sense 3 limited to the use of this procedure or to a sizereducing i'nedium volume necessary to carry it out, and with other and larger sizes of entering material and/or under other conditions automatic feed control and automatic regulation of load volume will be automatically secured with lesser sizereducing media volumes, and the load will be properly regulated and act as a valve to prevent any objectionable overfeedin It will be understood that whereas in the speci- 40 fication or claims I describe the reduction chamber as being substantially uniform or constant,

or generally or approximately uniform in cross section or in cross sectional area, from end to end thereof, I wish such terms to be used with suflicient flexibility to include not only slight variations in cross sectional area from point to point along the chamber, such as are inevitable i under ordinary manufacturing conditions, but also variations in cross sectional area resulting from inequality of wear, if any, and any other A slight variations incross sectional area to a degree insufflcient to impede or chan e the character of the reduction which takes place in such chamber or topreclude the described operation of the chamber contents in regulating feed. While there are in this application specifically described one embodiment and modifications thereof which the invention from its apparatus 0 aspect may assume in practice and onemode of practice of said invention from its method aspect, it will be understood that this embodiment may be modified in various other forms without departingvfrom its spirit or the scope of the appended claims.

What I claim as new and desireto secure by Letters Patent is: v 1. The method of reducing the size of material which comprises reciprocating along an arcuate path a quantity of size-reducing media, effecting reversals of movement without impact at the ends of the opposite passes thereof, discharging reduced material through one of the longitudinally extending boundaries of said path, and introducing material to be reduced through ingress means reduction zone which is substantially bisected by a vertical plane, subjecting the material to pressure reduction in said zone by effecting, wholly by the action on said load of friction and gravity, opposite traverses of said load in said zone which dispose the major part of said load alternately at opposite sides of said vertical plane and halting the load at the opposite ends of the zone by the action on the load of friction and gravity only, removingreduced material from said zone at a boundary thereof, continuously replacing thereduced material so removed with new material entering said zon'e generally radially with respect thereto, at all times maintaining the load substantially compact in said zone throughout the full cross section of the latter in adjacency to the points of entrance of new material to the zone.

3. The method of reducing material, which includes delivering material to be reduced to a reduction zone which lies in an annulus and which is bounded at its inner and outer radial limits by arcuate walls lying at the inner and outer peripheries of said annulus and whose ends are unobstructed, the relatively outer wall of which is perforated for the discharge of reduced material and the relatively inner wall of which is provided with orifice means for the admission of material to be reduced to said reduction zone,

and which reduction zone contains a mass of size-reducing media 'suflicient in volume to fill completely said reduction zone in all radial planes through which the material being reduced may enter thereinto, controlling the admission of material to be reduced to said reduction zone by normally confining entry thereof wholly through the interstices in said mass of sizereducing media, oscillating the mass of sizereducing media and material admitted thereto back and forth through an arcuate path within said annulus of such extent as normally to preclude entry of material to be reduced past the ends of the moving mass of size-reducing media and material admitted thereto, in all positions thereof in said path, so that the material to be reduced can normally pass through the reduction zone only by way of said interstices, and

discharging through said outer wall perforations.

the reduced material which has worked through the interstices of said moving mass of size-reducing media as said mass is oscillated along said arcuate path. r

4. In a size-reducing mill, a size-reducingchamber-providing device having circumferentially extending walls bounding an annular sizereducing chamber of substantially uniform cross sectional area on radial planes at all points throughout its arcuate extent and open internally throughout its full circumference, means for supporting said chamber-providing device for turning upon a generally horizontal axis at least substantially coincident with the axis of said annular chamber, means for causing said chamber-providing device to oscillate on said generally horizontal axis at a rate to impart movements to a load therein which continue at least mo- ;inentarily after the chamber becomes stationary at the extremes of the angular movement mereoi, means for supplying material to said annular chamber including a feed orifice opening through a wall of said chamber and providing an entrance through which material may enter the chamber freely and continuously except as the chamber load may impede the same and means for delivering material to said orifice while said for supporting said chamber-providing device for turning upon a generally horizontal axis at least substantially coincident with the axis of said annular chamber, means for causing said chamber-providing device to oscillate on said generally horizontal axis at a rate to impart movements to a load therein which continue at least momentarily after the chamber becomes stationary at the extremes of the angular movement thereof, means for supplying material to said annular chamber while chamber oscillation is in progress including feed orifice means opening through a portion of the walls for the chamber inwardly of the outermost portions of the latter and so located relative to said chamber that the median entially extending walls bounding an annular size-reducing chamber of substantially uniform cross sectional area on radial planes at all points throughout its arcuate extent and open internally throughout its full circumference, means for supporting said chamber-providing device for turning upon a generally horizontal axis at least substantially coincident with the axis of said annular chamber, means for causing said chamberproviding device to oscillate on said generally horizontal axis at a rate to impart movements to a load therein which continue at least momentarily after the chamber becomes stationary at the extremes of the angular movement thereof, means for supplying material to said annular chamber substantially continuously while chamber oscillation is in progress including feed orifice means opening through a portion of the walls for the chamber inwardly of the outermost portions of the latter and so located relative to said chamber that the median point in said feed orifice means is at substantially equal distances at opposite sides, of a vertical plane in which said axis lies when said chamber is in its opposite extremes of angular movement, and means for discharging material from the chamber through a relatively outer wall portion while the chamber-providing device is in oscillatiomsaid means for discharging material including discharge orifice means an'gularly displaced from the radial lines which pass through the most remote point in said feed orifice means.

substantially continuously '7. In a size-reducing mill, a size-reducingchamber-providing device having circumferentially extending walls bounding an annular sizereducing chamber of substantially uniform cross sectional area on radial planes at all points throughout its arcuate extent and open internally throughout its full circumference, means for supporting said chamber-providing device for turning upon a generally horizontal axis at least substantially coincident with the axis of said annular chamber, means for causing said chamber-providing device to oscillate on said generally horizontal axis at a rate to impart movements to a load therein which continue at least momentarily after the chamber becomes stationary at the extremes of the angular movement thereof, means for supplying material to said chamber while the chamber-providing device is in oscillation including a feed orifice means opening through a wall of the chamber and so related to the latter that said feed orifice means traverses an arcuate path at least the greater portion of which is below a horizontal plane in which said horizontal axis lies and which is at least substantially bisected by a vertical plane in which said horizontal axis lies, and means for discharging material through a wall of the chamber while the chamber-providing device is in oscillation.

8. In a size-reducing mill, a size-reducingchamber-providing device having circumferentially extending walls bounding an annular sizereducing chamber of substantially uniform cross sectional area on radial planes at all points throughout its arcuate extent and open internally throughout its fullcircumference, means for supporting said chamber-providing device for turning upon a generally horizontal axis at least substantially coincident with the axis of said annular chamber, means for causing said chamber-providing device to oscillate on said "generally horizontal axis at a rate and with an amplitude to impart movements to a load therein which continue at least momentarily after the chamber becomes stationary at the extremes of the angular movement thereof, means for supplying material to said chamber while the chamber-providing device is in oscillation including a feed orifice means opening through a wall of the chamber and so related to the latter that said feed orifice means traverses an arcuate path at least the greater portion of which is below a horizontal plane in which said horizontal axis lies and which is at least substantially bisected by a vertical plane in which said horizontal axis lies, and means for discharging material through a wall of the chamber while the chamber-providing device is in oscillation, said chamber having therein a charge of size-reducing media sufflcient in volume completely to cover said feed orifice means in all positions assumed by the latter during oscillation of said chamber-providing device.

9. In a size-reducing mill, an annular sizereducing chamber of substantially uniform cross sectional area on radial planes throughout its complete circumference, means for supporting said chamber for turning on an axis at least approximately in the same straight line with the axis of its annulus, means for supplying material to said chamber while the same is in motion including a feed opening in a wall thereof, means for discharging material of small enough size through a wall of sai'dchamber while the latter is in motion, a charge of size-reducing media in the chamber, and means for oscillating said chamber on said axis at a rate and with a stroke sufiicient to effect bodily arcuate movement of the chamber load relative to a stationary vertical plane bisecting the chamber, and relative to said chamber, at rates to create, respectively due to the motion of the load relative to such plane and relative to the chamber, pressures respectively radial and tangential of said chamher, for effecting size-reduction other than by attrition.

10. A size-reducing mill having, in combination, an annular size-reducing chamber of substantially uniform cross sectional area on radial planes and 360 in extent, means for supporting said chamber for turning upon a generally horizontal axis at least approximately in the same straight line with the axis of the chamber and stationary during the turning movements of said chamber, means for supplying material to the interior of said chamber while the latter is in motion including a feed opening through a wall of the chamber and means for conducting material to said opening while the chamber is in motion, means for discharging material of small enough size through a wall of said chamber while the latter is in motion, and means for oscillating said chamber on such generally horizontal axis, the conformation of said chamber and the angle and rate of oscillation of said chamber being predetermined to cause the positioning of the chamber load alternately largely at one side and largely at the other side of a vertical plane including such axis and to cause said load to travel between such positions and to move relative to said chamber to develop material-size-reducing pressures.

11. A size-reducing mill as defined in claim 10 in which the chamber has a charge of sizereducing media therein sufiicient, even in the absence of material to be reduced from the chamber, to mask said feed opening throughout its full extent circumferentially of said annulus, in all positions of said chamber during oscillation of the latter.

12. A size-reducing mill as defined in claim 10 in which the feed opening is so disposed that at the central positionof chamber oscillation the central portion of said feed opening is in its lowest position, and in which said means for discharging material of small enough size from the chamber includes openings out of line with the feed opening and spaced at opposite sides thereof circumferentially of said chamber.

13. In a mill, means providing an annular chamber supported for oscillatory movement about an at least approximately horizontal axis, said chamber being of substantially uniform cross sectional area at all points about its circumference and having its axis of curvature at least approximately in the same straight line with the axis of oscillatory movement, means for discharging material of small enough size from said chamber as the same oscillates, means for effecting the introduction of material to be reduced in size into said chamber substantially continuously while the same is in motion, and means for oscillating said chamber upon said axis at a rate and with a range of oscillation to cause the contents of said chamber to be reciprocated in an arcuate path between positions in which the major portion of the chamber contents is respectively at opposite sides of the vertical plane in which said at least approximately horizontal axis lies and at a rate to produce nular reduction zone which has its axis substanforces sufilcient to effect material-'size-reduction by radial pressure and also material-size-reduction by tangential thrusts of the load when. it

moves relative to the. chambers I 14. In a size-reducing mill, an annular sizereducing chamber of substantially uniform cross tially horizontal and which is of at least approximately uniform radial cross section, and in which said load is laterally but not longitudinally lestralnedby annular walls and which is of such normal size-reducing operation, alternately in opposite directions, to the conjoint forces of w gravity and friction, and intermediately causing one of the walls of the chamber while the chamber is in motion, a charge of size-reducing media in the chamber less than sufficient completely to fill the chamber but sufilcient in quantity at all times during normal chamber movement to mask the feed opening throughout its full extent circumferentiallytof the chamber. andmeans for oscillating said chamber on said axis at arate and with a stroke sufficient to establish and maintain bodily arcuate movement of the chamber load relative to a stationary vertical plane bisecting the chamber at a rate to create forces. due to the motion of the load sumcient to effect size-reduction other than by attrition.

15. A size-reducing mill having, in combination, means providing an annular size-reducing chamber of at least approximately uniform cross sectional area on radial planes at all points about its circumference, means 'for' supporting said- 5. 3

chamber providing means for 'oscillationabout a horizontal axis substantially coincident with the axis of chamber curvature, means for delivering.-

material to be reduced in size into said chamber as the latter is oscillated, means including discharge openings in the wall of the chamber for discharging material of small enough size from the chamber while the latter is in motion, a charge of size-reducing media in said chamber and means for oscillating said chamber on said axis 'to effect size reduction, the curvature and material. a

I 16. The method of reducingthe size of material which consists in confining the same in a mass consisting also of size reducing media within a reducing zone which is of annular conformation and of at least approximately uniform cross section on all planes extending radially of said zone throughout a mu 360 and which is so' disposed that its axis at least approximates horiso sontalness, imparting to the mass alternate opposite movements in and circumferentialiy of said zone atcsuch a rate as to produce centrifugalforces and tangential forces to which the materlal is subjected to eflect breaking thereof, ef-

footing the imparting of suchmovements to the mass wholly by the exertion thereon of frictional and gravitational forces, and continuously effect ing the subjection of new material to the sizereducing'operation by the withdrawal of material from said zone and its replacement by new material. y

17. The method of ,reducing the size of mate- 'rial which includes confining a load of which- .said materialforms atleast a part in an .an- '75 the same during normal size-reducing operation to be subjected, to stop the same prior to the reversals of movement, to the conjoint forces of friction and gravity only, discharging material of mall enough size from the load while thelatter is in motion. and supplying ,additional particles to be reduced to the load in a direction transverse -to the motion thereof and at points between the end of said reduction zone, and employing the load itself to regulate the introduction of the new particles. v

l8. Thiemethod of reducing material whichincludes moving a load of which said material forms at least a part, in the form of a relatively compact mass contacting with and shaped by the sides of its path, along a defined arcuate path whose cross'section for a substantial portion of its length said load at all times substantially fills} and which is so disposed that the load shall have at thecentral point of said path its radially inner longitudinal side higher than its outer side extending longitudinally of said path, alternately haltingtsaid load by gravity and by friction ipon the wallsdefining such path and eflecting reverse travel of said load by gravity and by friction upon the walls defining said path, in each case while the end surfaces of the load are free at all times. substantialy continuously withdrawing finely reduced material from the outer side of said load, substantially continuously survive ing additional particlesto be reduced to the inner side of said load in a direction transverse to the movement of the latter at the point of particle V supply, and employing the load itself as a moving barrier to control the entrance of additional particles.

19. The method of reducing the size of. material which consists in applying to a substantial compact mass of material particles and sizereducing media constrained to movement in a zone whose cross section it constantly substan' tially fills throughout a substantial portion of its length, a cycle of steps including imparting to the mass solely by gravity and'by the exertion of forces longitudinal of such are only upon the sides of said mass a throw alongan arcin anat least approximately vertical plane and constraining movement of said-mass to a continuation of such arc whereby centrifugal radial force and tangential forces act thereon, and aftera period of deceleration halting the movement hf such mass by the action oi! gravity and the application thereto of forces only upon the sides thereof, and then applying the same cycle in the reverse direction, and continuing said cycles in alternation to maintain an oscillation of said mass mass to travel throilgh through a relatively uniform arc. the conformstion of said arcand the intensity and the timing of the forces exerted on said mass being predetermined to restrict the movements of said arcs ofless than 360?.

ROBERT S. BUTLER. 

